First of all, you wouldn't want to try and machine down a 61mm or 62mm supercharger pulley as they are already designed / manufactured having the minimum amount of metal and bearing to be reasonably safe and functional.

Secondly, the 61mm / 62mm pulley mod pretty much creates the realistic limit of additional boost and the installation of those pulleys already require additional extensive modification to the fuel system to provide additional fuel supporting that increased boost.

Franky, if I had it to do over again I would just install a 65mm pulley and be happy. I'm not chasing 10ths of a second at the drag strip and would have undoubtedly been satisfied with the increased performance the 65mm pulley mod provides. Just saying . . .